Conventionally, to allow users to view structures of blood vessels through angiography image taking processes, an X-ray diagnosis apparatus performs a Digital Subtraction Angiography (DSA) image taking process. The DSA image taking process implements an image taking method by which an X-ray image (hereinafter, a “mask image”, as necessary) showing a state where no contrast material has been injected and an X-ray image (hereinafter, a “contrast image”, as necessary) showing a state where a contrast material has been injected are taken so as to perform a subtraction process between these images and to acquire a DSA image in which only the blood vessels are rendered.
In this situation, the DSA image is generated by performing the subtraction process between the two types of images, namely, the mask image and the contrast image. Thus, if the subject of the images moves, a positional misalignment may occur, in some situations, between the two types of images in a background element such as a bone, for example. In that situation, a region having signal intensities of pseudo signals occurs, although the region does not actually represent a blood vessel of which the contrast is enhanced by the contrast material. Such a region is viewed as an artifact in the DSA image.
To cope with this problem, a technique is known by which a subtraction process is performed after a position alignment process is performed on a mask image and a contrast image. According to this conventional technique, however, there is a certain limit to the visibility of angiography images.